I have a 97 SH 155k mileage with a very strange problem. Four months ago, while on the freeway at around 6000rpm, the vtec sound became intensely loud and the car bogged down severely so I let off on the gas back down to below vtec engagement rpm. There is now a very noticeable loss in power before vtec engages and, during vtec, the car is screaming much louder than normal but the power delivery is much weaker. There has not been a CEL the entire time...

Tested the car by driving it while being hooked to a Mac OBD2 scan tool, I've found out that the car isn't adding more fuel during the vtec rpm range. Also, I've found that disconnecting the vtec solenoid does not cause the computer to show a CEL or register a code. I'm driving the car fine, albeit slower due to the weak acceleration and without the vtec solenoid connected and still getting 25-26 mpg on the freeway (60+ miles a day commuter car) but still can't figure this out...

Timing from belt and flywheel are correct. I've changed all ignition components except distributor (plugs, wires, cap/rotor, replaced msd with stock coil) and fuel filter. Was contemplating changing O2 sensor but hesitating atm due to cost.

Anyone have advice on what to do next?




Modified by snorkelking at 5:09 AM 2/5/2007

 

Check your exhaust for bad leaks and check the cat.

 

i sort of had a similar problem...check oil cause mine was low causing vtec to bogg out i thought it was a fuel problem but i checked the oil and found the problem or do an oil change and valve job...it helped me get my low rpm power back well its even better then how i once used to have it....good luck on the find though..also check your throttle body cable it can also affect your to not be at full throttle....

 

I do have a minor exhaust leak but it's not bad. Checked the cat and the innards were still in good condition when a light is shined through. The oil level is at upper mark and the valves were checked after my last smog. Compression test was 200/175/175/200 and all fluids were checked...

About the smog... I had high nox levels at the low rpm part of the test, but it went normal for the higher rpm/speed part... I cleaned out my egr valve and used seafoam to pass. Nox levels were still noticeably higher in low rpm.

The CEL tests correctly when the key is turned. But shouldn't a CEL be registered if the vtec solenoid isn't hooked up? My biggest fear is that it is the ECU. Can Honda check if my ECU is working correctly?